X11 - XQueryTree produces "illegal storage acess" segfault when run

[SolitudeSF]

as araq pointed out, you dont declare pointers and pass them, you allocate 
objects and pass pointers to them, in this case for every returned value. this 
is not a nim related issue, you can see this if you look at any C code that 
uses this.
    
    
    import
      x11/xlib,
      x11/x
    
    var
      myDisplay: PDisplay
      myWindow: Window
      myWindowReturn: Window
      parentReturn: Window
      childrenReturn: PWindow
      numChildrenReturn: cuint
    
    myDisplay = XOpenDisplay(nil)
    if myDisplay == nil:
      quit "Unable to open display"
    
    myWindow = XDefaultRootWindow(myDisplay)
    echo repr(myDisplay)
    echo repr(myWindow)
    let myStatus: Status = XQueryTree(myDisplay, myWindow, addr myWindowReturn, 
addr parentReturn, addr childrenReturn, addr numChildrenReturn)
    
    if myStatus != 0:
      echo "Query successful!"
      # Process the windows here
    else:
      echo "Query failed"
    
    discard XCloseDisplay(myDisplay)
    
    
    Run